Australia have moved to Durban and will begin training at Kingsmead on Tuesday night (AEDT) ahead of Friday's opening Test, which marks their first red-ball series in the country for eight years.
The Proteas are without quick Lungi Ngidi for the start of the three-Test series, while pace spearhead Kagiso Rabada is fighting to recover from a hamstring injury in time to play in Durban.
But South Africa have picked eight fast bowlers in their preliminary squad with Anrich Nortje likely to return to the hosts' attack for his first Test in more than three years.
Head, meanwhile, has been Australia's x-factor for the past four years, going from a counter-attacking option at No.5 to opening the batting.
The 32-year-old has averaged 52.10 at the top, going from a temporary option there to permanent following a big home Ashes series.
But while England's attack was guilty of being wayward and inconsistent through last summer's Ashes, Border expects Head to be challenged in South Africa.
"Travis Head's done a very good job as an opener, but my gut feel is that he's better off in the middle order," Border, who will form part of Fox Sports' broadcast, said.
"He's done well where he's been. But against that bowling attack, he's in the firing line. That is for sure at the top of the order.
"Up until now, he's played really well against some so-so attacks you'd say
"But now you're going against the Real McCoy. So this will be a real test for him at the top of the order."
Cameron Green remains in serious doubt to play in Durban after suffering an abdominal strain in the final ODI and not featuring in Australia's weekend warm-up match.
If Green is out, one of Cooper Connolly, Nic Maddinson or the uncapped Sam Harper could come into the side, given Josh Inglis remains at home with a fractured finger.
Marnus Labuschagne's century in a warm-up game is expected to keep him at No.3, while Matt Renshaw has overcome a wrist injury to partner Head at the top.
Regardless, the concern for Border is alternatives to open if Head did go back down, with Nathan McSweeney and Sam Konstas having been trialled in recent years.
The former Test captain believes green Sheffield Shield wickets have made it difficult to find obvious candidates, with officials now pushing for the balance to go back slightly towards batters.
Openers averaged 31.23 across the Shield last year with Harper, Renshaw, and Victorian Blake MacDonald the best of them.
"Anyone who opens the batting in Shield cricket, you're facing a new ball against reasonable quality seamers on pitches that seam and bounce," Border said.
"So you're in the firing line. It's hard to make big scores to force the issue.
"You're making twenties and thirties. You might be batting your ass off and it's not a great-looking return.
"You look at the stats and say. 'he's not a bad player, but he's only averaging 22'.
"If we even that out a little bit more, then we'll find out who can and who can't play. It's just a bit of a lottery at the moment."
